Constraints on thick disc and halo parameters from HST photometry of field stars in the Galaxy

We analyse a sample of over 1000 stars from 32 fields imaged in the V and I bands with the Wide Field and Planetary Camera, on board of the Hubble Space Telescope. The fields are located at Galactic latitudes | b | >= 15deg and in various directions on the sky. We consider models for the structure of the Galaxy with different choices for the main parameters governing the shape and luminosity function of the thick disk and stellar halo. Comparing model predictions with the observed colour-magnitude diagram we are able to rule out an increasing or flat stellar luminosity function at the low-luminosity end. We also rule out large values of the vertical scale height of the thick disc, z_0, finding it to be in the range 800 <= z_0 <= 1200 pc. As for the local density normalization, values within the range 4 % <= n_0 <= 8 % seem to better reproduce the data. Our data essentially rule out a flattened stellar halo (c/a <~ 0.5) or models with both large local normalization and effective radii.Comment: 7 pages LaTeX, 9 Postscript figure

CFHT Adaptive Optics Observations of the Central Kinematics in M15

We have used an Imaging Fabry-Perot Spectrophotometer with the Adaptive Optics Bonnette on the Canada-France-Hawaii Telescope to measure stellar radial velocities in the globular cluster M15. An average seeing of 0.15" full-width at half maximum, with the best-seeing image having 0.09", allowed us to measure accurately the velocities for five stars within 1" of the center of M15. Our estimate of the second moment of the velocity distribution inside a radius of 2" is 11.5 km/s, the same value we find out to a radius of about 6". However, the projected net rotation does increase dramatically at small radii, as our previous observations led us to suspect. The rotation amplitude inside a radius of 3.4" is v = 10.4 +- 2.7 km/s and the dispersion after removing the rotation is sigma = 10.3 +- 1.4 km/s, so v/sigma = 1 in this region. In addition, the position angle (PA) of the projected rotation axis differs by 100 degrees from that of the net cluster rotation at larger radii. Current theoretical models do not predict either this large an increase in the rotation amplitude or such a change in the PA. However, a central mass concentration, such as a black hole, could possibly sustain such a configuration. The rotation increase is consistent with the existence of a central dark mass concentration equal to 2500 M_solar.Comment: 23 pages, emulateapj style, accepted for publication in The Astronomical Journal, Marc

Distances, ages, and epoch of formation of globular clusters

We review the results on distances and absolute ages of galactic globular clusters (GCs) obtained after the release of the Hipparcos catalogue. Several methods for the Population II local distance scale are discussed, exploiting NEW RESULTS for RR Lyraes in the Large Magellanic Cloud (LMC). We find that the so-called Short and Long Distance Scales may be reconciled whether a consistent reddening scale is adopted for Cepheids and RR Lyrae variables in the LMC. Distances and ages for the 9 clusters discussed in Paper I are re-derived using an enlarged sample of local subdwarfs, which includes about 90% of the metal-poor dwarfs with accurate parallaxes (Delta p/p < 0.12) in the whole Hipparcos catalogue. On average, our revised distance moduli are decreased by 0.04 mag with respect to Paper I. The corresponding age of the GCs is t=11.5+-2.6 Gyr (95% confidence range). The relation between Mv(ZAHB) and metallicity for the nine programme clusters turns out to be Mv(ZAHB)=(0.18+-0.09)([Fe/H]+1.5)+(0.53+-0.12).Thanks to Hipparcos the major contribution to the total error budget associated with the subdwarf fitting technique has been moved from parallaxes to photometric calibrations, reddening and metallicity scale. This total uncertainty still amounts to about +-0.12 mag. Comparing the corresponding (true) LMC distance modulus 18.64+-0.12 mag with other existing determinations, we conclude that at present the best estimate for the distance of the LMC is: 18.54+-0.03+-0.06, suggesting that distances from the subdwarf fitting method are 1 sigma too long. Consequently, our best estimate for the age of the GCs is revised to: Age = 12.9+-2.9 Gyr (95% confidence range). The best relation between Mv(ZAHB) and [Fe/H] is: Mv(ZAHB) =(0.18+-0.09)([Fe/H]+1.5)+(0.63+-0.07).Comment: 76 pages, 6 encapsulated figures and 6 tables. Latex, uses aasms4.sty. Revised and improved version, with new data on field RR Lyraes in LMC. Accepted in the Astrophysical Journa

Water Dynamics at Protein Interfaces: Ultrafast Optical Kerr Effect Study

The behavior of water molecules surrounding a protein can have an important bearing on its structure and function. Consequently, a great deal of attention has been focused on changes in the relaxation dynamics of water when it is located at the protein surface. Here we use the ultrafast optical Kerr effect to study the H-bond structure and dynamics of aqueous solutions of proteins. Measurements are made for three proteins as a function of concentration. We find that the water dynamics in the first solvation layer of the proteins are slowed by up to a factor of 8 in comparison to those in bulk water. The most marked slowdown was observed for the most hydrophilic protein studied, bovine serum albumin, whereas the most hydrophobic protein, trypsin, had a slightly smaller effect. The terahertz Raman spectra of these protein solutions resemble those of pure water up to 5 wt % of protein, above which a new feature appears at 80 cm–1, which is assigned to a bending of the protein amide chain

Etrace Express: manual de programa para análisis de riesgo de elementos traza en fertilizantes inorgánicos.

bitstream/item/77789/1/doc-291.pd

Potássio liberado por biocarvão de lodo de esgoto enriquecido com agromineral e ácido oxálico.

A correta destinação do lodo do esgoto (LE) tem se tornado um grande desafio para sociedade. O uso do LE in natura como fertilizante pode acarretar contaminação por microrganismos patogênicos e metais tóxicos. O biocarvão de LE (BLE), obtido pela pirólise do LE, é uma alternativa segura para viabilizar o uso agrícola do LE. O BLE é um fertilizante multinutrientes, porém apresenta baixa concentração de potássio (K). Uma forma de tornar o BLE um fertilizante completo seria a adição de fontes alternativas de K, produzidas a partir da moagem de rochas silicáticas, como os sienitos. No entanto, a baixa solubilidade do agromineral tem se tornado um empecilho para o uso desse insumo. Nesse sentido, este trabalho tem por objetivo avaliar a dinâmica de liberação de K oriundo dos fertilizantes à base de BLE enriquecidos com pó de rocha e ácido orgânico (oxálico) (FEs). Para isso, os FEs foram incubados e avaliados nos períodos de 12 horas e 20 dias. Os resultados indicam que o ácido oxálico potencializou a solubilização de K oriundo dos fertilizantes à base de biocarvão e agromineral. Como essa é uma nova linha de pesquisa, mais estudos devem ser realizados para ajustar as concentrações e a forma de aplicação do ácido oxálico a fim de aumentar a eficiência desses fertilizantes

State space modelling and data analysis exercises in LISA Pathfinder

LISA Pathfinder is a mission planned by the European Space Agency to test the key technologies that will allow the detection of gravitational waves in space. The instrument on-board, the LISA Technology package, will undergo an exhaustive campaign of calibrations and noise characterisation campaigns in order to fully describe the noise model. Data analysis plays an important role in the mission and for that reason the data analysis team has been developing a toolbox which contains all the functionalities required during operations. In this contribution we give an overview of recent activities, focusing on the improvements in the modelling of the instrument and in the data analysis campaigns performed both with real and simulated data.Comment: Plenary talk presented at the 9th International LISA Symposium, 21-25 May 2012, Pari

Field Blue Stragglers and Related Mass Transfer Issues

This chapter contains my impressions and perspectives about the current state of knowledge about field blue stragglers (FBS) stars, drawn from an extensive literature that I searched. I conclude my review of issues that attend FBS and mass transfer, by a brief enumeration of a few mildly disquieting observational facts.Comment: Chapter 4, in Ecology of Blue Straggler Stars, H.M.J. Boffin, G. Carraro & G. Beccari (Eds), Astrophysics and Space Science Library, Springe